This invention relates to Ultrasonically prepared NiO and ZnO nanoparticles utilized in the making of NiO-ZnO based photo-catalyst for the degradation of organic pollutants in water.
BACKGROUND OF THE INVENTION
US20200316577A1 Mixed-phase TiO2 nanofibers prepared via a sol-gel technique followed by electrospinning and calcination are provided as photocatalysts. The calcination temperature is adjusted to control the rutile phase fraction in TiO2 nanofibers relative to the anatase phase. Post-calcined TiO2 nanofibers composed of 38 wt % rutile and 62 wt % anatase exhibited the highest initial rate constant of UV photocatalysis. This can be attributed to the combined influences of the fibers' specific surface areas and their phase compositions.
Research Gap: We used ultrasonically prepared ZnO and NiO nanoparticles in the making of composite based catalyst. Synthetic method is highly economical. We used NiO-ZnO catalyst in the photo-degradation of methyl organge and Rhodamine B.
CN102921416B relates to a silver doped grapheme-zinc oxide nano composite photocatalytic material and a method for preparing the same and belongs to the technical field of nano composite materials and photocatalysis. Graphite oxide is subjected to ultrasonic dispersion to obtain a dispersion solution of graphene oxide; precursors of silver ions and zinc ions are added in the dispersion solution of the graphene oxide, and the mixture is placed into a reaction kettle to be subjected to hydro-thermal treatment to be prepared into the silver doped grapheme-zinc oxide nano composite photocatalytic material in situ after the pH is regulated to an alkaline condition. Photocatalytic degradation experiments show that the silver doped grapheme-zinc oxide nano composite photocatalytic material prepared through the method has good adsorption and visible light photocatalytic degradation effects on rhodamine B and is an ideal nano composite photocatalytic material.
Research Gap: We used mixed metal oxides in the synthesis of catalysts instead of graphene oxide. We used the prepared catalysts in degradation of two different dyes instead of one.
US20200316577A1 discloses a composite photocatalyst, preparation and use thereof are disclosed. The composite photocatalyst is composed of metal oxide and quantum dot material. Based on the photocatalyst, the percentage content of the metal oxide is from 80 to 99.99% by mass, and the percentage content of the quantum dot material is from 0.01 to 20% by mass. The metal oxide is zinc oxide or titanium oxide. The quantum dot material is graphene quantum dot or carbon quantum dot. The preparation is that the metal oxide and quantum dot material are stirred, mixed, ultrasonicated and dried in sequence, and the photocatalyst is obtained. Compared with other photocatalysts, the catalyst has higher catalytic efficiency and faster catalytic rate for Rhodamine B and provides more sufficient and more comprehensive utilization of sunlight.
Research Gap: We used only metal oxides in the preparation of catalyst instead of quantum dots. The final catalyst is utilized in the degradation of two different dyes instead of one.
SUMMARY OF THE INVENTION
The introduction of organic pollutants such as harmful dyes in water system is a serious issue in the world. These dyes and their metabolites are definitely harmful to all living organisms and cause many life-threatening problems. The photo-catalytic method used in the degradation of these metabolites is cost-effective, efficient and applicable in large scale operations. In this work, we used very efficient and low-cost ultrasonic method in the preparation of NiO-ZnO based photo-catalyst. This catalyst is utilized in the degradation of methyl orange and Rhodamine B from aqueous solution. The azo anionic dye methyl orange is a common and water-soluble organic synthetic dye which is highly poisonous, carcinogenic, and teratogenic. Rhodamine B causes oxidative stress in cells and tissues. It also causes liver problems and acute poisoning.
Discloses herein A method of preparation of NiO and ZnO nanoparticles comprising taking 100 ml of ethanolic (5 %) 1 M zinc acetate and nickel nitrate solution in separate conical flasks and sonicated for 1 h; adding few drops of 0.1 M NaOH in above mixtures under constant ultra-sonication; Precipitating of ZnO and NiO nanoparticles obtained; again, sonicating the mixture for 2 hours; Separating the obtained nanoparticles using centrifugation method and washed with double distilled water and absolute alcohol; Washing ZnO and NiO nanoparticles are completely dried in hot air oven and calcined at 2000C for 4 hour.

DETAILED DESCRIPTION OF THE INVENTION
1. Ultrasonication method for synthesis of NiO and ZnO nanoparticles:

2. Preparation of NiO-ZnO catalyst and its Photo-catalytic activity:
NiO-ZnO catalyst is prepared by mixing of NiO and ZnO 1:3 ratio under ultrasonic conditions. The prepared catalysts is completely dried in hot air oven. Under ultraviolet radiation (mercury vapour lamp; 175 w), photocatalytic activity is carried out using various parameters such as time, dosage, concentration, pH, and temperature. An adequate amount of NiO-ZnO is combined with 100 ml of dye-containing solution and shaken under appropriate ultraviolet radiation. The concentration of dye is measured using a UV-Visible spectrophotometer when the reactions are completed. The following is a summary of the photocatalytic work:

Novel Features of Invention:
? Very low-cost and easily operative method.
? No requirements of expensive instruments for the synthesis.
? The synthetic method can definitely be utilized in the large scale production of photo-catalysts.
? Optimization of reaction parameters.

Claims:
1. A method of preparation of NiO and ZnO nanoparticles comprises
Taking 100 ml of ethanolic (5 %) 1 M zinc acetate and nickel nitrate solution in separate conical flasks and sonicated for 1 h;
adding few drops of 0.1 M NaOH in above mixtures under constant ultra-sonication;
Precipitating of ZnO and NiO nanoparticles obtained; again, sonicating the mixture for 2 hours;
Separating the obtained nanoparticles using centrifugation method and washed with double distilled water and absolute alcohol;
Washing ZnO and NiO nanoparticles are completely dried in hot air oven and calcined at 2000C for 4 h.
2. The method as claimed in claim 1, wherein NiO-ZnO catalyst is prepared by mixing of NiO and ZnO 1:3 ratio under ultrasonic conditions.
3. The method as claimed in claim 1, wherein the prepared catalysts is completely dried in hot air oven.
4. The method as claimed in claim 1, wherein under ultraviolet radiation (mercury vapour lamp; 175 w), photocatalytic activity is carried out using various parameters such as time, dosage, concentration, pH, and temperature.
5. The method as claimed in claim 1, wherein an adequate amount of NiO-ZnO is combined with 100 ml of dye-containing solution and shaken under appropriate ultraviolet radiation.
6. The method as claimed in claim 1, wherein the concentration of dye is measured using a UV-Visible spectrophotometer when the reactions are completed.